Advances in Amine-Surface Functionalization of Inorganic Adsorbents for Water Treatment and Antimicrobial Activities: A Review

In the last decade, adsorption has exhibited promising and effective outcomes as a treatment technique for wastewater contaminated with many types of pollutants such as heavy metals, dyes, pharmaceuticals, and bacteria. To achieve such effectiveness, a number of potential adsorbents have been synthesized and applied for water remediation and antimicrobial activities. Among these inorganic adsorbents (INAD), activated carbon, silica, metal oxide, metal nanoparticles, metal–organic fibers, and graphene oxide have been evaluated. In recent years, significant efforts have been made in the development of highly efficient adsorbent materials for gas and liquid phases. For gas capture and water decontamination, the most popular and known functionalization strategy is the chemical grafting of amine, due to its low cost, ecofriendliness, and effectiveness. In this context, various amines such as 3-aminopropyltriethoxysilane (APTES), diethanolamine (DEA), dendrimer-based polyamidoamine (PAMAM), branched polyethyleneimine (PEI), and others are employed for the surface modification of INADs to constitute a large panel of resource and low-cost materials usable as an alternative to conventional treatments aimed at removing organic and inorganic pollutants and pathogenic bacteria. Amine-grafted INAD has long been considered as a promising approach for the adsorption of both inorganic and organic pollutants. The goal of this review is to provide an overview of surface modifications through amine grafting and their adsorption behavior under diverse conditions. Amine grafting strategies are investigated in terms of the effects of the solvent, temperature, and the concentration precursor. The literature survey presented in this work provides evidence of the significant potential of amine-grafted INAD to remove not only various contaminants separately from polluted water, but also to remove pollutant mixtures and bacteria.

An overview on biocatalysts immobilization on textiles: Preparation, progress and application in wastewater treatment

The immobilization of biocatalysts or other bioactive components often means their transformation from a soluble to an insoluble state by attaching them to a solid support material. Various types of fibrous textiles from both natural and synthetic sources have been studied as suitable support material for biocatalysts immobilization. Strength, inexpensiveness, high surface area, high porosity, pore size, availability in various forms, and simple preparation/functionalization techniques have made textiles a primary choice for various applications. This led to the concept of a new domain called-biocatalysts immobilization on textiles. By addressing the growing advancement in biocatalysts immobilization on textile, this study provides the first detailed overview on this topic based on the terms of preparation, progress, and application in wastewater treatment. The fundamental reason behind the necessity of biocatalysts immobilized textile as well as the potential preparation methods has been identified and discussed. The overall progress and performances of biocatalysts immobilized textile have been scrutinized and summarized based on the form of textile, catalytic activity, and various influencing factors. This review also highlighted the potential challenges and future considerations that can enhance the pervasive use of such immobilized biocatalysts in various sustainable and green chemistry applications.

Development of a multifunctional graphene/Fe-loaded polyester textile: robust electrical and catalytic properties

A graphene/Fe loaded polyester fabric (PET) with robust electrical and catalytic properties has been successfully developed for the first time via a simple coating-incorporation method using hyperbranched poly(amidoamine) (PAMAM) dendrimer as the binder. Both graphene oxide (GO/rGO) and zerovalent iron (Fe0) nanoparticles were loaded on the polyester fabric surface before and after chemical grafting of PAMAM. Full characterization of fabrics before and after modifications has been performed by sessile droplet goniometry, ζ-potential, K/S coating evenness, SEM, XPS, FTIR, TGA and DSC analyses. The results showed successful and uniform coating of GO/rGO and loading of Fe0 on PET and also showed the correlation between the type of chemical moiety responsible for uniform GO coating, high Fe0 loading and their electrical and catalytic activities. Sheet resistance (Rsh) analysis was carried out to measure the conductivity of the samples. The lowest Rsh (corresponding to high conductivity) was found in PET-PAM-rGO-Fe0 (0.74 ± 0.13 kΩ sq-1) followed by PET-rGO-Fe0 (1.32 ± 0.18 kΩ sq-1), PET-PAM-rGO (2.96 ± 0.08 kΩ sq-1) and PET-rGO (3.41 ± 0.34 kΩ sq-1). Furthermore, Fe0-loaded samples were found to be effective in the catalytic removal of toxic water pollutants (crystal violet dye) with ∼99% removal of pollutants in around one hour, as observed by UV-vis spectroscopy. The relatively high electrical conductivity and catalytic activity of PET-PAM-rGO-Fe0 are related to the role played by PAMAM in the uniform rGO coating and high Fe0 loading. These findings are of great importance as they allow envisaging the development of multifunctional textiles for combined smart and green chemistry application.

Statistical modeling and optimization of heterogeneous Fenton-like removal of organic pollutant using fibrous catalysts: a full factorial design

This work focuses on the optimization of heterogeneous Fenton-like removal of organic pollutant (dye) from water using newly developed fibrous catalysts based on a full factorial experimental design. This study aims to approximate the feasibility of heterogeneous Fenton-like removal process and optionally make predictions from this approximation in a form of statistical modeling. The fibrous catalysts were prepared by dispersing zerovalent iron nanoparticles on polyester fabrics (PET) before and after incorporation of either polyamidoamine (PAMAM, -NH2) dendrimer, 3-(aminopropyl) triethoxysilane (APTES, -Si-NH2) or thioglycerol (SH). The individual effect of two main factors [pH (X1) and concentration of hydrogen peroxide-[H2O2]μl (X2)] and their interactional effects on the removal process was determined at 95% confidence level by an L27 design. The results indicated that increasing the pH over 5 decreases the dye removal efficiency whereas the rise in [H2O2]μl until equilibrium point increases it. The principal effect of the type of catalysts (PET-NH2-Fe, PET-Si-NH2-Fe, and PET-SH-Fe) did not show any statistical significance. The factorial experiments demonstrated the existence of a significant synergistic interaction effect between the pH and [H2O2]μl as expressed by the values of the coefficient of interactions and analysis of variance (ANOVA). Finally, the functionalization of the resultant fibrous catalysts was validated by electrokinetic and X-ray photoelectron spectroscopy analysis. The optimization made from this study are of great importance for rational design and scaling up of fibrous catalyst for green chemistry and environmental applications.

Modification of fibrous membrane for organic and pathogenic contaminants removal: from design to application

In this study, a flexible multifunctional fibrous membrane for heterogeneous Fenton-like removal of organic and pathogenic contaminants from wastewater was developed by immobilizing zerovalent iron nanoparticles (Fe-NPs) on an amine/thiol grafted polyester membrane. Full characterization of the resulting polyester membranes allowed validation of successful grafting of amine/thiol (NH₂ or SH) functional groups and immobilization of Fe-NPs (50–150 nm). The Fenton-like functionality of iron immobilized fibrous membranes (PET–Fe, PET–Si–NH₂–Fe, PET–NH₂–Fe, and PET–SH–Fe) in the presence of hydrogen peroxide (H₂O₂) was comparatively studied in the removal of crystal violet dye (50 mg L⁻¹). The effect of pH, amount of iron and H₂O₂ concentration on dye removal was systematically investigated. The highest dye removal yield reached 98.87% in 22 min at a rate constant 0.1919 min⁻¹ (R² = 95.36) for PET–SH–Fe providing 78% toxicity reduction assessed by COD analysis. These membranes could be reused for up to seven repeated cycles. Kinetics and postulated mechanism of colour removal were proposed by examining the above results. In addition, the resultant membranes showed substantial antibacterial activity against pathogenic bacteria (Staphylococcus epidermidis, Escherichia coli) strains studied through disc diffusion-zone inhibitory and optical density analysis. These findings are of great importance because they provide a prospect of textile-based flexible catalysts in heterogeneous Fenton-like systems for environmental and green chemistry applications.

Multifunctional fibrous membrane for heterogeneous Fenton-like removal of organic and pathogenic contaminants from wastewater was developed by immobilizing zerovalent iron nanoparticles (Fe-NPs) on an amine/thiol grafted polyester membrane.

Gamma radiation-assisted in situ synthesis of palladium nanoparticles supported on ethylenediamine-functionalized polypropylene fabric as an efficient catalyst for reduction of 4-nitrophenol

Immobilization of Pd nanometals on a functionalized non-woven polypropylene fabric offers heterogenous catalytic activity in many chemical transformations and convenient separation from the reaction mixture.

Dopamine Grafted Iron-Loaded Waste Silk for Fenton-Like Removal of Toxic Water Pollutants

Dispersion of iron was achieved on waste silk fibers (wSF) after grafting of polydopamine (PDA). The catalytic activity of the resulting material (wSF-DA/Fe) was investigated in Fenton-like removal of toxic aromatic dyes (Methylene Blue, Cationic Violet X-5BLN, and Reactive Orange GRN) water. The dye removal yield reached 98%, 99%, and 98% in 10–40 min for Methylene Blue, Cationic Violet X-5BLN, and Reactive Orange GRN, respectively. The catalytic activity was explained in terms of the effects of temperature, dyes, and electrolytes. In addition, the kinetic study showed that the removal of dyes followed pseudo-1st order adsorption kinetics. These findings allow envisaging the preparation of fiber-based catalysts for potential uses in environmental and green chemistry.

Surface modification of polyester fabric using plasma-dendrimer for robust immobilization of glucose oxidase enzyme

Robust immobilization of glucose oxidase (GOx) enzyme was achieved on poly(ethylene terephthalate) nonwoven fabric (PN) after integration of favourable surface functional groups through plasma treatments [atmospheric pressure-AP or cold remote plasma-CRP (N₂ + O₂)] and/or chemical grafting of hyperbranched dendrimers [poly-(ethylene glycol)-OH or poly-(amidoamine)]. Absorption, stability, catalytic behavior of immobilized enzymes and reusability of resultant fibrous bio-catalysts were comparatively studied. Full characterization of PN before and after respective modifications was carried out by various analytical, instrumental and arithmetic techniques. Results showed that modified polyester having amine terminal functional groups pledged better surface property providing up to 31% enzyme loading, and 81% active immobilized enzymes. The activity of the enzyme was measured in terms of interaction aptitude of GOx in a given time to produce hydrogen peroxide using colorimetric assay. The immobilized GOx retained 50% of its original activity after being reused six (06) times and exhibited improved stability compared with the free enzyme in relation to temperature. The reaction kinetics, loading efficiency, leaching, and reusability analysis of enzyme allowed drawing a parallel to the type of organic moiety integrated during GOx immobilization. In addition, resultant fibrous bio-catalysts showed substantial antibacterial activity against pathogenic bacteria strains (Staphylococcus epidermidis and Escherichia coli) in the presence of oxygen and glucose. These results are of great importance because they provide proof-of-concept for robust immobilization of enzymes on surface-modified fibrous polyester fabric for potential bio-industrial applications.